Autism, ADHD, mental retardation and behavior problems in 100 individuals with 22q11 deletion syndrome

Cortical Development Requires Mesodermal Expression of Tbx1, a Gene Haploinsufficient in 22q11.2 Deletion Syndrome

In mammals, proper temporal control of neurogenesis and neural migration during embryonic development ensures correct formation of the cerebral cortex. Changes in the distribution of cortical projection neurons and interneurons are associated with behavioral disorders and psychiatric diseases, including schizophrenia and autism, suggesting that disrupted cortical connectivity contributes to the brain pathology. TBX1 is the major candidate gene for 22q11.2 deletion syndrome (22q11.2DS), a chromosomal deletion disorder characterized by a greatly increased risk for schizophrenia. We have previously shown that Tbx1 heterozygous mice have reduced prepulse inhibition, a behavioral abnormality that is associated with 22q11.2DS and nonsyndromic schizophrenia. Here, we show that loss of Tbx1 disrupts corticogenesis in mice by promoting premature neuronal differentiation in the medio-lateral embryonic cortex, which gives rise to the somatosensory cortex (S1). In addition, we found altered polarity in both radially migrating excitatory neurons and tangentially migrating inhibitory interneurons. Together, these abnormalities lead to altered lamination in the S1 at the terminal stages of corticogenesis in Tbx1 null mice and similar anomalies in Tbx1 heterozygous adult mice. Finally, we show that mesoderm-specific inactivation of Tbx1 is sufficient to recapitulate the brain phenotype indicating that Tbx1 exerts a cell nonautonomous role in cortical development from the mesoderm.

Genetics implicate common mechanisms in autism and schizophrenia: synaptic activity and immunity

The diagnosis of debilitating psychiatric disorders like autism spectrum disorder (ASD) and schizophrenia (SCHZ) is on the rise. These are severe conditions that lead to social isolation and require lifelong professional care. Improved diagnosis of ASD and SCHZ provides early access to medication and therapy, but the reality is that the mechanisms and the cellular pathology underlying these conditions are mostly unknown at this time. Although both ASD and SCHZ have strong inherited components, genetic risk seems to be distributed in hundreds of variants, each conferring low risk. The poor understanding of the genetics of ASD and SCHZ is a significant hurdle to developing effective treatments for these costly conditions. The recent implementation of next-generation sequencing technologies and the creation of large consortia have started to reveal the genetic bases of ASD and SCHZ. Alterations in gene expression regulation, synaptic architecture and activity and immunity seem to be the main cellular mechanisms contributing to both ASD and SCHZ, a surprising overlap given the distinct phenotypes and onset of these conditions. These diverse pathways seem to converge in aberrant synaptic plasticity and remodelling, which leads to altered connectivity between relevant brain regions. Continuous efforts to understand the genetic basis of ASD and SCHZ will soon lead to significant progress in the mechanistic understanding of these prominent psychiatric disorders and enable the development of disease-modifying therapies for these devastating conditions.

Risk factors for the existence of attention deficit hyperactivity disorder symptoms in children with autism spectrum disorders

Over the years, several authors have reported symptoms of attention deficit hyperactivity disorder (ADHD) in patients with autism spectrum disorders (ASD); however, studies on the risk factors of ADHD symptoms in children with ASD are lacking. The aim of this cross-sectional study was to identify the risk factors for the development of ADHD symptoms in children with ASD. The sample consisted of 67 children with ASD who were assessed with Conner's Parent Rating Scale-Revised (CPRS-R), and with a semi-structured detailed interview administered to parents, to collect a series of clinical data such as coexisting somatic and neuropsychiatric problems and familial and pre/peri/postpartum risk factors. We found that 55% of ASD children exceeded the cut-off of CPRS-R Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV), total scale. The univariate analyses showed that children's age (P=0.048), motor delay (P=0.039), enuresis (P=0.014), allergies (P<0.01), comorbid oppositional defiant disorder (P=0.026) and intellectual disabilities comorbidities (P=0.034) were associated to the CPRS-R DSM-IV total score. Some familial predictors such as neuropsychiatric family history of intellectual disabilities (P=0.003) and psychosis (P=0.039) were related to the CPRS-R DSM-IV total score. In particular, a model including allergies (P=0.000) and family history of psychosis (P=0.03) explained 25% (corrected R²=0.25) of the variance of the DSM-IV ADHD score. In conclusion, we identified some risk factors associated with the development of ADHD symptoms in ASD children that need to be studied further.

Categorical versus dimensional approaches to autism-associated intermediate phenotypes in 22q11.2 microdeletion syndrome

BACKGROUND

22q11.2 Microdeletion syndrome (22q11DS) is associated with elevated rates of autism spectrum disorders (ASDs), although the diagnosis is controversial. In order to determine whether there is a biological substrate of ASD in 22q11DS, we examined neurocognitive and structural neuroanatomic differences between those with 22q11DS and an ASD diagnosis (22q11DS-ASD+) and those with 22q11DS without ASD (22q11DS-ASD-); we then determined whether these differences were better characterized within a categorical or dimensional framework.

METHODS

We collected multiple neurocognitive measures and high-resolution T1-weighted scans on 116 individuals (29 22q11DS-ASD+, 32 22q11DS-ASD-, 55 typically developing controls) between 6 and 26 years of age. Measures of subcortical volume, cortical thickness (CT), and surface area were extracted using the FreeSurfer image analysis suite. Group differences in neurocognitive and neuroanatomic measures were assessed; regression analyses were then performed to determine whether a categorical or dimensional measure of ASD was a better predictor of neurocognitive impairment and/or neuroanatomic abnormalities observed in 22q11DS-ASD+.

RESULTS

In comparison to 22q11DS-ASD-, 22q11DS-ASD+ participants exhibited decreased bilateral hippocampal CT and decreased right amygdala volumes. Those with 22q11DS-ASD+ also showed slowed processing speed and impairments in visuospatial and facial memory. Neurocognitive impairments fit a dimensional model of ASD, whereas reductions in parahippocampal CT were best explained by a categorical measure of ASD.

CONCLUSIONS

A combination of categorical and dimensional measures of ASD may provide the most comprehensive understanding of ASDs in 22q11DS.

[Formula: see text]Executive functioning and its relation to ASD and ADHD symptomatology in 22q11.2 deletion syndrome

Children with 22q11.2 deletion syndrome (22q11DS; velo-cardio-facial-syndrome) are at risk for the developmental disorders, attention deficit hyperactivity disorder (ADHD) and autism spectrum disorder (ASD). In this study, the relation between executive functioning (EF) and the severity of ADHD and ASD symptoms is examined, since EF is known to be important in relation to emotional and behavioral problems. The participants consist of 58 children (38 females) with a mean age of 13.5 years (SD 2.6). Standardized assessment was used to evaluate the severity of ASD and ADHD symptomatology. The major aspects of EF, i.e., cognitive flexibility, inhibition, sustained attention, distractibility, working memory and reaction speed, were evaluated. The profile of EF in 22q11DS was found to be characterized by weaker performance compared to the norms on all subdomains of EF. Poor cognitive flexibility and inhibition, as well as high distractibility, were found to be related to more severe ASD symptoms, while poor quality of sustained attention and high distractibility were found to be related to more severe ADHD symptoms. It is concluded that children with 22q11DS experience impairments in EF, and that the degree of impairment on specific EF subdomains is related to the severity of ASD and/or ADHD symptomatology. These results may help in defining the mediating role of neurocognitive dysfunctions in the development of social and behavioral problems in 22q11DS.

Cognitive phenotype and psychiatric disorder in 22q11.2 deletion syndrome: A review

The behavioural phenotype of 22q11.2 deletion syndrome syndrome (22q11DS), one of the most common human multiple anomaly syndromes, frequently includes intellectual disability (ID) together with high risk of diagnosis of psychotic disorders including schizophrenia. Candidate cognitive endophenotypes include problems with retrieval of contextual information from memory and in executive control and focussing of attention. 22q11DS may offer a model of the relationship between ID and risk of psychiatric disorder. This paper reviews research on the relationship between the cognitive phenotype and the development of psychiatric disorders in 22q11DS. Aspects of cognitive function including verbal I.Q., visual memory, and executive function, are associated with mental health outcome in people with 22q11DS. This relationship may result from a common neurobiological basis for the cognitive difficulties and psychiatric disorders. Some of the cognitive difficulties experienced by people with 22q11DS, especially in attention, memory retrieval, and face processing, may, however, in themselves constitute risk factors for development of hallucinations and paranoid delusions. Future research into factors leading to psychiatric disorder in people with 22q11DS should include assessment of social and psychological factors including life events, symptoms associated with trauma, attachment, and self-esteem, which together with cognitive risk factors may mediate mental health outcome.

22q11.2 duplication syndrome: elevated rate of autism spectrum disorder and need for medical screening

Background

Widespread use of microarray technology has led to increasing identification of 22q11.2 duplication syndrome (22q11.2DupS), the reciprocal syndrome of the well-characterized 22q11.2 deletion syndrome (22q11.2DS). Individuals with 22q11.2DS have elevated rates of community diagnoses of autism spectrum disorder (ASD), schizophrenia, and a range of medical problems and birth defects that necessitate extensive medical screening. Case reports of 22q11.2DupS include patients with ASD, fewer medical problems, and no schizophrenia; however, no prospective cohort study has been reported. The goals of the study were to (1) characterize the neuropsychiatric functioning of a cohort of individuals with 22q11.2DupS in comparison to large samples of typically developing controls (TDCs), ASD and 22q11.2DS; (2) estimate the prevalence of ASD in 22q11.2DupS; (3) determine whether the indications that prompted the genetic testing in 22q11.2DupS differ from 22q11.2DS and (4) determine whether comprehensive medical screening should be recommended for those diagnosed with 22q11.2DupS.

Methods

Medical characterization was done by parental questionnaire and medical chart review of individuals with 22q11.2DupS (n = 37) and 22q11.2DS (n = 101). Neuropsychiatric characterization of children with 22.11.2DupS, 22q11.2DS, TDCs, and ASD was done by parent-report questionnaires; in addition, the ASD and 22q11.2DupS groups received the Autism Diagnostic Interview-Revised and Autism Diagnostic Observation Schedule.

Results

Individuals with 22q11.2DupS, 22q11.2DS, and ASD had significantly impaired social interaction and adaptive behavior skills compared to TDCs. Overall, 38 % of children aged 2–18 with 22q11.2DupS had community diagnoses of ASD, but fewer (14–25 %) met on the basis of best clinical judgment that included ADI-R and ADOS data. Indications for genetic testing were significantly different for 22q11.2DupS and 22q11.2DS, with the deletions more commonly tested because of birth defects or medical problems, and the duplications because of developmental delay. However, when the screening protocol for 22q11.2DS was applied to the 22q11.2DupS sample, several medical problems were identified that would pose significant risk if left undetected.

Conclusions

22q11.2DupS has a high rate of ASD at 14–25 %, among the highest of any genetic disorder. Prospective medical screening should be done for all patients with 22q11.2DupS, including those diagnosed due to developmental delays and ASD alone.

Electronic supplementary material

The online version of this article (doi:10.1186/s13229-016-0090-z) contains supplementary material, which is available to authorized users.

Schizophrenia Spectrum Disorders in a Danish 22q11.2 Deletion Syndrome Cohort Compared to the Total Danish Population--A Nationwide Register Study

OBJECTIVE

Cross-sectional studies have shown associations between 22q11.2 deletion syndrome and schizophrenia. However, large-scale prospective studies have been lacking. We, therefore, conducted the first large-scale population based study on the risk of being diagnosed with schizophrenia in persons identified with 22q11.2 deletion syndrome.

METHODS

Danish nationwide registers were linked to establish a cohort consisting of all Danish citizens born during 1955-2004 and the cohort was followed from January 1, 1994 until December 31, 2013. Data were analyzed using survival analyses and adjusted for calendar year, age, sex, and parental mental health history.

RESULTS

A total of 156 individuals with 22q11.2 deletion syndrome were identified, out of which 6 individuals were diagnosed with schizophrenia spectrum disorders following identification with 22q11 deletion syndrome. Identified carriers of 22q11.2 deletion had an 8.13(95% CI: 3.65-18.09) fold increased risk of schizophrenia spectrum disorder.

CONCLUSIONS

Carriers of a 22q11.2 deletion who had been clinically identified had a highly increased risk of schizophrenia spectrum disorders.

The role of COMT and plasma proline in the variable penetrance of autistic spectrum symptoms in 22q11.2 deletion syndrome

This paper examines how COMT¹⁵⁸ genotypes and plasma proline levels are associated with variable penetrance of social behavioural and social cognitive problems in 22q11.2 deletion syndrome (22q11DS). Severity of autistic spectrum symptoms of 45 participants with 22q11DS was assessed using the Autism Diagnostic Interview Revised. Face and facial emotion recognition was evaluated using standardized computer-based test-paradigms. Associations with COMT¹⁵⁸ genotypes and proline levels were examined. High proline levels and poor face recognition in individuals with the COMT^MET allele, and poor facial emotion recognition, explained almost 50% of the variance in severity of autism symptomatology in individuals with 22q11DS. High proline levels and a decreased capacity to break down dopamine as a result of the COMT^MET variant are both relevant in the expression of the social phenotype in patients. This epistatic interaction effect between the COMT¹⁵⁸ genotype and proline on the expression of social deficits in 22q11DS shows how factors other than the direct effects of the deletion itself can modulate the penetrance of associated cognitive and behavioural outcomes. These findings are not only relevant to our insight into 22q11DS, but also provide a model to better understand the phenomenon of variable penetrance in other pathogenic genetic variants.

The clinical presentation of attention deficit-hyperactivity disorder (ADHD) in children with 22q11.2 deletion syndrome

BACKGROUND

Although attention deficit-hyperactivity disorder (ADHD) is the most prevalent psychiatric disorder in children with 22q11.2DS, it remains unclear whether its clinical presentation is similar to that in children with idiopathic ADHD. The aim of this study is to compare the ADHD phenotype in children with and without 22q11.2DS by examining ADHD symptom scores, patterns of psychiatric comorbidity, IQ and gender distribution.

METHODS

Forty-four children with 22q11.2DS and ADHD (mean age = 9.6), 600 clinic children (mean age = 10.8) and 77 children with ADHD from a population cohort (mean age = 10.8) participated in the study. Psychopathology was assessed using parent-report research diagnostic instruments.

RESULTS

There was a higher proportion of females in the 22q11.2DS ADHD sample in relation to the clinical sample (χ(2)  = 18.2, P < 0.001). The 22q11.2DS group showed a higher rate of ADHD inattentive subtype (χ(2)  = 114.76, P < 0.001), and fewer hyperactive-impulsive symptoms compared to the clinical group (z = 8.43, P < 0.001). The 22q11.2DS ADHD group parents reported fewer oppositional defiant disorder/conduct disorder symptoms (z = 6.33, P < 0.001) and a higher rate of generalized anxiety disorder (χ(2)  = 4.56, P = 0.03) in relation to the clinical group. Two percent of the 22q11.2 DS ADHD sample had received ADHD treatment. The results were similar when the 22q11.2 ADHD group was compared to the population cohort ADHD group.

CONCLUSIONS

The clinical presentation of ADHD and patterns of co-morbidity in 22q11.2DS is different from that in idiopathic ADHD. This could lead to clinical under-recognition of ADHD in this group. Examining psychopathology in 22q11.2DS can provide insights into the genetic origins of psychiatric problems with implications beyond the 22q11.2DS population.

New discoveries in schizophrenia genetics reveal neurobiological pathways: A review of recent findings

Schizophrenia research has undergone a recent transformation. By leveraging large sample sizes, genome-wide association studies of common genetic variants have approximately tripled the number of candidate genetic loci. Rare variant studies have identified copy number variants that are schizophrenia risk loci. Among these, the 3q29 microdeletion is now known to be the single largest schizophrenia risk factor. Next-generation sequencing studies are increasingly used for rare variant association testing, and have already facilitated identification of large effect alleles. Collectively, recent findings implicate voltage-gated calcium channel and cytoskeletal pathways in the pathogenesis of schizophrenia. Taken together, these results suggest the possibility of imminent breakthroughs in the molecular understanding of schizophrenia.

Comorbidity of intellectual disability confounds ascertainment of autism: implications for genetic diagnosis

While recent studies suggest a converging role for genetic factors towards risk for nosologically distinct disorders including autism, intellectual disability (ID), and epilepsy, current estimates of autism prevalence fail to take into account the impact of comorbidity of these disorders on autism diagnosis. We aimed to assess the effect of comorbidity on the diagnosis and prevalence of autism by analyzing 11 years (2000-2010) of special education enrollment data on approximately 6.2 million children per year. We found a 331% increase in the prevalence of autism from 2000 to 2010 within special education, potentially due to a diagnostic recategorization from frequently comorbid features such as ID. The decrease in ID prevalence equaled an average of 64.2% of the increase of autism prevalence for children aged 3-18 years. The proportion of ID cases potentially undergoing recategorization to autism was higher (P = 0.007) among older children (75%) than younger children (48%). Some US states showed significant negative correlations between the prevalence of autism compared to that of ID while others did not, suggesting state-specific health policy to be a major factor in categorizing autism. Further, a high frequency of autistic features was observed when individuals with classically defined genetic syndromes were evaluated for autism using standardized instruments. Our results suggest that current ascertainment practices are based on a single facet of autism-specific clinical features and do not consider associated comorbidities that may confound diagnosis. Longitudinal studies with detailed phenotyping and deep molecular genetic analyses are necessary to completely understand the cause of this complex disorder.

Caracterização do perfil comportamental e de competência social de indivíduos com a síndrome del22q11.2

Resumo:OBJETIVO:caracterizar os problemas comportamentais e de competência social de indivíduos com a síndrome del22q11.2 e compará-los com indivíduos com desenvolvimento típico, segundo informação dos pais.MÉTODOS:participaram desta pesquisa 24 pais de indivíduos de ambos os gêneros, entre seis e 18 anos, sendo 12 indivíduos com a síndrome del22q11.2 (grupo amostral) e 12 indivíduos com desenvolvimento típico (grupo controle). Foi aplicado o inventário comportamental "Child Behavior Checklist (CBCL)".RESULTADOS:oito dos 12 indivíduos com a síndrome foram classificados como "clínico" nas escalas de comportamento e Problemas Internalizantes; cinco dos 12 indivíduos do grupo amostral foram classificados como "clínico" quanto às escalas de comportamento e Problemas Externalizantes. Nas habilidades de competência social, dez dos 12 indivíduos do grupo amostral foram classificados como "clínico".CONCLUSÃO:indivíduos com diagnóstico da síndrome del22q11.2 apresentaram, segundo opinião dos pais, problemas comportamentais e de competência social, em diferentes graus de comprometimento. Quando realizada a comparação entre os grupos pode-se observar diferenças estatisticamente significantes em variáveis dos comportamentos externalizantes e dos comportamentos internalizantes. Desta forma, concluí-se que o grupo amostral apresenta comportamentos mais alterados quando comparados ao grupo controle.

Transcriptome Profiling of Peripheral Blood in 22q11.2 Deletion Syndrome Reveals Functional Pathways Related to Psychosis and Autism Spectrum Disorder

Background

22q11.2 Deletion Syndrome (22q11DS) represents one of the greatest known genetic risk factors for the development of psychotic illness, and is also associated with high rates of autistic spectrum disorders (ASD) in childhood. We performed integrated genomic analyses of 22q11DS to identify genes and pathways related to specific phenotypes.

Methods

We used a high-resolution aCGH array to precisely characterize deletion breakpoints. Using peripheral blood, we examined differential expression (DE) and networks of co-expressed genes related to phenotypic variation within 22q11DS patients. Whole-genome transcriptional profiling was performed using Illumina Human HT-12 microarrays. Data mining techniques were used to validate our results against independent samples of both peripheral blood and brain tissue from idiopathic psychosis and ASD cases.

Results

Eighty-five percent of 22q11DS individuals (N = 39) carried the typical 3 Mb deletion, with significant variability in deletion characteristics in the remainder of the sample (N = 7). DE analysis and weighted gene co-expression network analysis (WGCNA) identified expression changes related to psychotic symptoms in patients, including a module of co-expressed genes which was associated with psychosis in 22q11DS and involved in pathways associated with transcriptional regulation. This module was enriched for brain-expressed genes, was not related to antipsychotic medication use, and significantly overlapped with transcriptional changes in idiopathic schizophrenia. In 22q11DS-ASD, both DE and WGCNA analyses implicated dysregulation of immune response pathways. The ASD-associated module showed significant overlap with genes previously associated with idiopathic ASD.

Conclusion

These findings further support the use of peripheral tissue in the study of major mutational models of diseases affecting the brain, and point towards specific pathways dysregulated in 22q11DS carriers with psychosis and ASD.

An urgent need for experimental animal model of autism in drug development

Construct, face and predictive validities are necessary for any disease model. Although rodent models are used to investigate the neurobiology of autism, however, till date there is no such ideal animal model which can fulfill all the above said validities. Available drug therapy to treat autism is very limited and less effective. In this review, we summarize the work done with rodent models of autism and highlight different validities. We found that, very few studies have studied all the validities in a single study and none of the study fulfilled all the validities. We also reviewed the drugs used in the treatment of autism. Here we propose the limitations of available animal models. We also propose the urgent need of additional models to fulfill all the validities and to understand autism in a better way.

Association Between Method of Cerebral Protection During Neonatal Aortic Arch Surgery and Attention Deficit/Hyperactivity Disorder

BACKGROUND

Neonates undergoing repair of the aortic arch are at risk for adverse neurodevelopmental outcomes, including attention deficit/hyperactivity disorder (ADHD). The purpose of this study was to compare the effect of deep hypothermic circulatory arrest versus regional cerebral perfusion on the long-term outcome of ADHD.

METHODS

This study is a cross-sectional observational study of ADHD in children who underwent neonatal aortic arch surgery. Attention Deficit/Hyperactivity Disorder-IV surveys were used to determine the prevalence of ADHD. Review of the medical records was performed to determine the primary method of cerebral protection and to extract related surgical variables.

RESULTS

Surveys were sent to parents of 134 children, with 57 surveys completed (43%). The percentage of children classified as having ADHD was 44%. Children with a diagnosis of interrupted aortic arch had the highest prevalence of ADHD (85%). Multivariate analysis demonstrated that interrupted aortic arch was associated with an increased ADHD inattention score (p < 0.01), and a decreased Child Health Questionnaire-50 psychosocial score (p < 0.01). Low Child Health Questionnaire-50 psychosocial summary scores are associated with increased behavioral problems and are lower in patients with ADHD.

CONCLUSIONS

Attention deficit/hyperactivity disorder is common after neonatal aortic arch surgery and may be primarily related to genetic predisposition. We found insufficient evidence to show that either deep hypothermic circulatory arrest or regional cerebral perfusion decreased the risk of ADHD.

Developmental trajectories in 22q11.2 deletion

Chromosome 22q11.2 deletion syndrome (22q11.2DS), a neurogenetic condition, is the most common microdeletion syndrome affecting 1 in 2,000-4,000 live births and involving haploinsufficiency of ∼50 genes resulting in a multisystem disorder. Phenotypic expression is highly variable and ranges from severe life-threatening conditions to only a few associated features. Most common medical problems include: congenital heart disease, in particular conotruncal anomalies; palatal abnormalities, most frequently velopharyngeal incompetence (VPI); immunodeficiency; hypocalcemia due to hypoparathyroidism; genitourinary anomalies; severe feeding/gastrointestinal differences; and subtle dysmorphic facial features. The neurocognitive profile is also highly variable, both between individuals and during the course of development. From infancy onward, motor delays (often with hypotonia) and speech/language deficits are commonly observed. During the preschool and primary school ages, learning difficulties are very common. The majority of patients with 22q11.2DS have an intellectual level that falls in the borderline range (IQ 70-84), and about one-third have mild to moderate intellectual disability. More severe levels of intellectual disability are uncommon in children and adolescents but are more frequent in adults. Individuals with 22q11.2DS are at an increased risk for developing several psychiatric disorders including attention deficit with hyperactivity disorder (ADHD), autism spectrum disorder (ASD), anxiety and mood disorders, and psychotic disorders and schizophrenia. In this review, we will focus on the developmental phenotypic transitions regarding cognitive development in 22q11.2DS from early preschool to adulthood, and on the changing behavioral/psychiatric phenotype across age, on a background of frequently complex medical conditions.

Modeling a model: Mouse genetics, 22q11.2 Deletion Syndrome, and disorders of cortical circuit development

Understanding the developmental etiology of autistic spectrum disorders, attention deficit/hyperactivity disorder and schizophrenia remains a major challenge for establishing new diagnostic and therapeutic approaches to these common, difficult-to-treat diseases that compromise neural circuits in the cerebral cortex. One aspect of this challenge is the breadth and overlap of ASD, ADHD, and SCZ deficits; another is the complexity of mutations associated with each, and a third is the difficulty of analyzing disrupted development in at-risk or affected human fetuses. The identification of distinct genetic syndromes that include behavioral deficits similar to those in ASD, ADHC and SCZ provides a critical starting point for meeting this challenge. We summarize clinical and behavioral impairments in children and adults with one such genetic syndrome, the 22q11.2 Deletion Syndrome, routinely called 22q11DS, caused by micro-deletions of between 1.5 and 3.0 MB on human chromosome 22. Among many syndromic features, including cardiovascular and craniofacial anomalies, 22q11DS patients have a high incidence of brain structural, functional, and behavioral deficits that reflect cerebral cortical dysfunction and fall within the spectrum that defines ASD, ADHD, and SCZ. We show that developmental pathogenesis underlying this apparent genetic "model" syndrome in patients can be defined and analyzed mechanistically using genomically accurate mouse models of the deletion that causes 22q11DS. We conclude that "modeling a model", in this case 22q11DS as a model for idiopathic ASD, ADHD and SCZ, as well as other behavioral disorders like anxiety frequently seen in 22q11DS patients, in genetically engineered mice provides a foundation for understanding the causes and improving diagnosis and therapy for these disorders of cortical circuit development.

ASD, ADHD, mental health conditions and psychopharmacology in neurogenetic syndromes: parent survey

BACKGROUND

There are a number of neurogenetic syndromes with well described behavioural phenotypes including fragile X syndrome, Prader-Willi syndrome, Williams syndrome and velo-cardio-facial syndrome (VCFS). Autism spectrum disorder (ASD), attention deficit hyperactivity disorder (ADHD) and psychiatric conditions are often associated with the syndromes.

METHOD

Parents (n = 381) of school-aged children with one of the four syndromes in the UK and Ireland were asked whether their child had been professionally diagnosed with ASD, ADHD or a mental health condition. Parents were also asked whether their child had been prescribed medication for behavioural or psychiatric reasons.

RESULTS

The highest level of reported diagnoses of ASD and ADHD was in fragile X syndrome. In all syndrome groups, lower rates of diagnosis were reported in comparison to previously published research. Prescribing of medication for behavioural/psychiatric reasons was highest in fragile X syndrome although the highest usage of melatonin was in Williams syndrome.

CONCLUSION

Reasons for a lower recognition of ASD, ADHD and mental health conditions in clinical practice compared with research studies may include 'diagnostic overshadowing' due to presence of intellectual disability and a genetic syndrome. However, there may also be a lack of belief in the utility of such diagnoses in neurogenetic syndromes among relevant professionals and/or lack of access to professionals with sufficient expertise in the recognition of such diagnoses in those with neurogenetic syndromes. The low rates of prescribing of medication for behavioural/psychiatric reasons may reflect the low level of clinical diagnoses or lack of belief in the utility of psychopharmacology in this population.

The many etiologies of neonatal hypocalcemic seizures

Seizures during the neonatal period have a broad differential diagnosis. Unlike in developing countries where hypovitaminosis D and hypocalcemia constitutes a major cause of infantile seizures, the number of neonatal seizures attributed to hypocalcemia in developed countries has decreased dramatically due to the improvement of infant formulas and vitamin D supplementation. In these countries, most infants that present with hypocalcemic seizures have underlying endocrinological etiologies rather than dietary insufficiencies. Here, we describe 3 cases of neonatal seizures due to hypocalcemia. Although the symptoms and calcium concentrations at presentation were similar in all 3 cases, the course of the disease and the final diagnosis for each were distinct. The cases are presented along with a brief review of the pathophysiology, differential diagnosis, and treatment of neonatal hypocalcemia.

Is child intelligence associated with parent and sibling intelligence in individuals with developmental disorders? An investigation in youth with 22q11.2 deletion (velo-cardio-facial) syndrome

Children with 22q11.2 deletion syndrome (22q11DS), a copy-number variation (CNV) genetic disorder, demonstrate a great deal of variability in IQ scores and are at particular risk for cognitive difficulties, with up to 45% experiencing intellectual disability. This study explored the IQ relationship between individuals with 22q11DS, their parents and their siblings. Participants included individuals with 22q11DS, unaffected siblings and community controls, who participated in a longitudinal study of 22q11DS. Significant associations between proband and relative (parent, sibling) IQ scores were found. Results suggest that the cognitive functioning of first-degree relatives could be a useful marker of general genetic background and/or environmental effects, and can explain some of the large phenotypic variability in 22q11DS. These findings underscore the importance of including siblings and parents in studies of 22q11DS whenever possible.

Social impairments in chromosome 22q11.2 deletion syndrome (22q11.2DS): autism spectrum disorder or a different endophenotype?

High prevalence of autism spectrum disorders (ASD) has been reported in 22q11.2DS, although this has been based solely on parent report measures. This study describes the presence of ASD using a procedure more similar to that used in clinical practice by incorporating history (Social Communication Questionnaire) AND a standardized observation measure (Autism Diagnostic Observation Schedule) and suggests that ASD is not as common as previously reported in 22q11.2DS. Differences in methodology, along with comorbid conditions such as anxiety, likely contribute to false elevations in ASD prevalence and information from multiple sources should be included in the evaluation of ASD.

Psychopathology in adults with 22q11 deletion syndrome and moderate and severe intellectual disability

BACKGROUND

22q11 deletion syndrome (22q11DS) is associated with mild or borderline intellectual disability (ID). There are hardly any reports on subjects with 22q11DS with moderate or severe ID, and therefore its behavioural and psychiatric characteristics are unknown.

METHOD

We describe behavioural and psychiatric characteristics of 33 adults with 22q11DS and a Full-Scale IQ (FSIQ) below 55. Participants were divided into two groups: one group having a FSIQ ≤ 55 caused by intellectual decline (n = 21) and one group with a FSIQ ≤ 55 who had always functioned at this level (n = 12).

RESULTS

High scores on psychopathology sub-scales were found for both subgroups. 22q11DS patients with intellectual decline showed higher rates of co-morbid psychopathology, particularly psychosis. Furthermore, psychosis and intellectual decline were positive correlated.

CONCLUSION

This is the first report addressing adult patients with 22q11DS and moderate to severe ID. Overall we found high levels of psychopathology with higher scores of psychopathology in the intellectual decline group. Life time psychosis seems to be related to deterioration.

Neuropathology of 22q11 deletion syndrome in an infant

The 22q11 deletion syndrome (22q11DS) is the most common microdeletion syndrome in humans and one of the chromosomal conditions most associated with psychosis and autism spectrum disorder. To date, only 2 neuropathologic studies of 22q11DS have been reported. Findings included polymicrogyria, neuronal heterotopias, excess subcortical white-matter (interstitial) neurons, significant white-matter gliosis/hypomyelination, and microvasculopathy. Here, we report on a 3-month-old infant with documented 22q11DS, tetralogy of Fallot, and pulmonary atresia. The brain exhibited tortuous cerebral vessels and proportionately smaller occipital lobes. Histologic examination revealed cerebral white-matter pathology and subtle differences in cortical lamination, including an excess of interstitial white-matter neurons compared with a sample of age-matched controls. There was a 15% increase in DARPP-32+ medium spiny neurons in the anterior-superior caudate. In this first neuropathologic report of an infant with 22q11DS, the findings were similar to previously reported manifestations and are likely secondary to perfusion issues, developmental microvasculopathy, and abnormal frontal cortical development.

Cortical interneurons require Jnk1 to enter and navigate the developing cerebral cortex

Proper assembly of cortical circuitry relies on the correct migration of cortical interneurons from their place of birth in the ganglionic eminences to their place of terminal differentiation in the cerebral cortex. Although molecular mechanisms mediating cortical interneuron migration have been well studied, intracellular signals directing their migration are largely unknown. Here we illustrate a novel and essential role for c-Jun N-terminal kinase (JNK) signaling in guiding the pioneering population of cortical interneurons into the mouse cerebral cortex. Migrating cortical interneurons express Jnk proteins at the entrance to the cortical rudiment and have enriched expression of Jnk1 relative to noninterneuronal cortical cells. Pharmacological blockade of JNK signaling in ex vivo slice cultures resulted in dose-dependent and highly specific disruption of interneuron migration into the nascent cortex. Time-lapse imaging revealed that JNK-inhibited cortical interneurons advanced slowly and assumed aberrant migratory trajectories while traversing the cortical entry zone. In vivo analyses of JNK-deficient embryos supported our ex vivo pharmacological data. Deficits in interneuron migration were observed in Jnk1 but not Jnk2 single nulls, and those migratory deficits were further exacerbated when homozygous loss of Jnk1 was combined with heterozygous reduction of Jnk2. Finally, genetic ablation of Jnk1 and Jnk2 from cortical interneurons significantly perturbed migration in vivo, but not in vitro, suggesting JNK activity functions to direct their guidance rather than enhance their motility. These data suggest JNK signaling, predominantly mediated by interneuron expressed Jnk1, is required for guiding migration of cortical interneurons into and within the developing cerebral cortex.

The comorbidity of ADHD and autism spectrum disorder

ADHD and autism spectrum disorder are common psychiatric comorbidities to each another. In addition, there is behavioral, biological and neuropsychological overlap between the two disorders. There are also several important differences between autism spectrum disorder and ADHD. Treatment strategies for the comorbid condition will also be reviewed. Future areas of research and clinical need will be discussed.

High rate of disease-related copy number variations in childhood onset schizophrenia

Copy number variants (CNVs) are risk factors in neurodevelopmental disorders, including autism, epilepsy, intellectual disability (ID) and schizophrenia. Childhood onset schizophrenia (COS), defined as onset before the age of 13 years, is a rare and severe form of the disorder, with more striking array of prepsychotic developmental disorders and abnormalities in brain development. Because of the well-known phenotypic variability associated with pathogenic CNVs, we conducted whole genome genotyping to detect CNVs and then focused on a group of 46 rare CNVs that had well-documented risk for adult onset schizophrenia (AOS), autism, epilepsy and/or ID. We evaluated 126 COS probands, 69 of which also had a healthy full sibling. When COS probands were compared with their matched related controls, significantly more affected individuals carried disease-related CNVs (P=0.017). Moreover, COS probands showed a higher rate than that found in AOS probands (P<0.0001). A total of 15 (11.9%) subjects exhibited at least one such CNV and four of these subjects (26.7%) had two. Five of 15 (4.0% of the sample) had a 2.5-3 Mb deletion mapping to 22q11.2, a rate higher than that reported for adult onset (0.3-1%) (P<0.001) or autism spectrum disorder and, indeed, the highest rate reported for any clinical population to date. For one COS subject, a duplication found at 22q13.3 had previously only been associated with autism, and for four patients CNVs at 8q11.2, 10q22.3, 16p11.2 and 17q21.3 had only previously been associated with ID. Taken together, these findings support the well-known pleiotropic effects of these CNVs suggesting shared abnormalities early in brain development. Clinically, broad CNV-based population screening is needed to assess their overall clinical burden.

Psychiatric disorders in 22q11.2 deletion syndrome are prevalent but undertreated

BACKGROUND

Chromosome 22q11.2 deletion syndrome (22q11DS) is a common genetic disorder with high rates of psychosis and other psychopathologies, but few studies discuss treatment. Our aim was to characterize the prevalence and treatment of major psychiatric illnesses in a well-characterized sample of individuals with 22q11DS.

METHOD

This was a cross-sectional study of 112 individuals aged 8 to 45 years with a confirmed diagnosis of 22q11DS. Each participant was administered a modified Schedule for Affective Disorders and Schizophrenia for School-Age Children (K-SADS) and the Structured Interview for Prodromal Syndromes (SIPS). Phenotypes assessed were threshold and subthreshold psychosis, depression, mania, generalized and separation anxiety, obsessions/compulsions, inattention/hyperactivity and substance use. Histories of mental health care and current psychotropic treatment were obtained.

RESULTS

Psychopathology was common, with 79% of individuals meeting diagnostic criteria for a disorder at the time of assessment. Diagnoses of psychosis were made in 11% of cases, attenuated positive symptom syndrome (APS) in 21%, and 47% experienced significant subthreshold symptoms. Peak occurrence of psychosis risk was during adolescence (62% of those aged 12-17 years). Criteria for a mood disorder were met by 14%, for anxiety disorder 34% and for attention deficit hyperactivity disorder (ADHD) 31%. Mental health care had been received by 63% of individuals in their lifetime, but only 40% continued therapy and 39% used psychotropics. Antipsychotics were used by 42% of participants with psychosis and none of the participants with APS. Half of those at risk for psychosis were receiving no mental health care.

CONCLUSIONS

Psychopathology is common in 22q11DS but is not adequately treated or clinically followed. Particular attention should be paid to subthreshold psychotic symptoms, especially in adolescents.

Contribution of congenital heart disease to neuropsychiatric outcome in school-age children with 22q11.2 deletion syndrome

Children with 22q11.2 deletion syndrome (22q11DS) present with congenital heart disease (CHD) and high prevalence of psychiatric disorders and neurocognitive deficits. Although CHD has been implicated in neurodevelopment, its role in the neuropsychiatric outcome in 22q11DS is poorly understood. We investigated whether CHD contributes to the high prevalence of psychiatric disorders and neurocognitive impairments in 22q11DS. Fifty-four children ages 8-14 years with 22q11DS and 16 age-matched non-deleted children with CHD participated. They were assessed using semi-structured interviews and a Computerized Neurocognitive Battery. CHD status was assessed using available medical records. Prevalence of psychiatric disorders and cognitive profiles were compared among the groups. There were no significant differences between the prevalence of psychiatric disorders in the 22q11DS with and without CHD. In 22q11DS with CHD, the prevalence rates were 41% anxiety disorders, 37% ADHD and 71% psychosis spectrum. In 22q11DS without CHD, the rates were 33% anxiety disorders, 41% ADHD and 64% psychosis spectrum. In comparison, the non-deleted CHD group had lower rates of psychopathology (25% anxiety disorders, 6% ADHD, and 13% psychosis spectrum). Similarly, the 22q11DS groups, regardless of CHD status, had significantly greater neurocognitive deficits across multiple domains, compared to the CHD-only group. We conclude that CHD in this sample of children with 22q11.2DS does not have a major impact on the prevalence of psychiatric disorders and is not associated with increased neurocognitive deficits. These findings suggest that the 22q11.2 deletion status itself may confer significant neuropsychiatric vulnerability in this population.

The 22q11.2 deletion syndrome as a window into complex neuropsychiatric disorders over the lifespan

Evidence is rapidly accumulating that rare, recurrent copy number variants represent large effect risk factors for neuropsychiatric disorders. 22q11.2 deletion syndrome (22q11DS) (velocardiofacial syndrome or DiGeorge syndrome) is the most common known contiguous gene deletion syndrome and is associated with diverse neuropsychiatric disorders across the life span. One of the most intriguing aspects of the syndrome is the variability in clinical and cognitive presentation: children with 22q11DS have high prevalence of autism spectrum, attention deficit, and anxiety disorders, as well as psychotic-like features, and up to 30% of adolescents and adults develop schizophrenia-like psychosis. Recently, cases of early-onset Parkinson's disease in adults have been reported, collectively suggesting a role for disrupted dopaminergic neurotransmission in the observed neuropsychiatric phenotypes. There is also some evidence that 22q11DS-associated autism spectrum disorder and schizophrenia represent two unrelated phenotypic manifestations, consistent with a neuropsychiatric pleiotropy model. This genetic lesion thus provides a unique model for the discovery of specific genomic risk and (potentially) protective factors for neuropsychiatric disease. Here, we provide an overview of neuropsychiatric findings to date, which highlight the value of this syndrome in mapping the developmental trajectory of dimensional phenotypes that traverse multiple diagnostic categories. Potential sources of genetic variability that may contribute to the disorder's heterogeneous presentation are reviewed. Because of its known genetic etiology, animal models can readily be developed that recapitulate specific aspects of the syndrome. Future research directions involve translational models and potential for drug screenable targets in the context of this human model system.

Does epilepsy in multiplex autism pedigrees define a different subgroup in terms of clinical characteristics and genetic risk?

BACKGROUND

Autism spectrum disorders (ASD) and epilepsy frequently occur together. Prevalence rates are variable, and have been attributed to age, gender, comorbidity, subtype of pervasive developmental disorder (PDD) and risk factors. Recent studies have suggested disparate clinical and genetic settings depending on simplex or multiplex autism. The aim of this study was to assess: 1) the prevalence of epilepsy in multiplex autism and its association with genetic and non-genetic risk factors of major effect, intellectual disability and gender; and 2) whether autism and epilepsy cosegregate within multiplex autism families.

METHODS

We extracted from the Autism Genetic Resource Exchange (AGRE) database (n = 3,818 children from 1,264 families) all families with relevant medical data (n = 664 children from 290 families). The sample included 478 children with ASD and 186 siblings without ASD. We analyzed the following variables: seizures, genetic and non-genetic risk factors, gender, and cognitive functioning as assessed by Raven's Colored Progressive Matrices (RCPM) and Vineland Adaptive Behavior Scales (VABS).

RESULTS

The prevalence of epilepsy was 12.8% in cases with ASD and 2.2% in siblings without ASD (P <10-5). With each RCPM or VABS measure, the risk of epilepsy in multiplex autism was significantly associated with intellectual disability, but not with gender. Identified risk factors (genetic or non-genetic) of autism tended to be significantly associated with epilepsy (P = 0.052). When children with prematurity, pre- or perinatal insult, or cerebral palsy were excluded, a genetic risk factor was reported for 6/59 (10.2%) of children with epilepsy and 12/395 (3.0%) of children without epilepsy (P = 0.002). Finally, using a permutation test, there was significant evidence that the epilepsy phenotype co-segregated within families (P <10-4).

CONCLUSIONS

Epilepsy in multiplex autism may define a different subgroup in terms of clinical characteristics and genetic risk.

Cognitive ability is associated with altered medial frontal cortical circuits in the LgDel mouse model of 22q11.2DS

We established a relationship between cognitive deficits and cortical circuits in the LgDel model of 22q11 Deletion Syndrome (22q11DS)-a genetic syndrome with one of the most significant risks for schizophrenia and autism. In the LgDel mouse, optimal acquisition, execution, and reversal of a visually guided discrimination task, comparable to executive function tasks in primates including humans, are compromised; however, there is significant individual variation in degree of impairment. The task relies critically on the integrity of circuits in medial anterior frontal cortical regions. Accordingly, we analyzed neuronal changes that reflect previously defined 22q11DS-related alterations of cortical development in the medial anterior frontal cortex of the behaviorally characterized LgDel mice. Interneuron placement, synapse distribution, and projection neuron frequency are altered in this region. The magnitude of one of these changes, layer 2/3 projection neuron frequency, is a robust predictor of behavioral performance: it is substantially and selectively lower in animals with the most significant behavioral deficits. These results parallel correlations of volume reduction and altered connectivity in comparable cortical regions with diminished executive function in 22q11DS patients. Apparently, 22q11 deletion alters behaviorally relevant circuits in a distinct cortical region that are essential for cognitive function.

Copy number variation at 22q11.2: from rare variants to common mechanisms of developmental neuropsychiatric disorders

Recently discovered genome-wide rare copy number variants (CNVs) have unprecedented levels of statistical association with many developmental neuropsychiatric disorders, including schizophrenia, autism spectrum disorders, intellectual disability and attention deficit hyperactivity disorder. However, as CNVs often include multiple genes, causal genes responsible for CNV-associated diagnoses and traits are still poorly understood. Mouse models of CNVs are in use to delve into the precise mechanisms through which CNVs contribute to disorders and associated traits. Based on human and mouse model studies on rare CNVs within human chromosome 22q11.2, we propose that alterations of a distinct set of multiple, noncontiguous genes encoded in this chromosomal region, in concert with modulatory impacts of genetic background and environmental factors, variably shift the probabilities of phenotypes along a predetermined developmental trajectory. This model can be further extended to the study of other CNVs and may serve as a guide to help characterize the impact of genes in developmental neuropsychiatric disorders.

Patch-clamp recordings and calcium imaging followed by single-cell PCR reveal the developmental profile of 13 genes in iPSC-derived human neurons

Molecular genetic studies are typically performed on homogenized biological samples, resulting in contamination from non-neuronal cells. To improve expression profiling of neurons we combined patch recordings with single-cell PCR. Two iPSC lines (healthy subject and 22q11.2 deletion) were differentiated into neurons. Patch electrode recordings were performed on 229 human cells from Day-13 to Day-88, followed by capture and single-cell PCR for 13 genes: ACTB, HPRT, vGLUT1, βTUBIII, COMT, DISC1, GAD1, PAX6, DTNBP1, ERBB4, FOXP1, FOXP2, and GIRK2. Neurons derived from both iPSC lines expressed βTUBIII, fired action potentials, and experienced spontaneous depolarizations (UP states) ~2 weeks before vGLUT1, GAD1 and GIRK2 appeared. Multisite calcium imaging revealed that these UP states were not synchronized among hESC-H9-derived neurons. The expression of FOXP1, FOXP2 and vGLUT1 was lost after 50 days in culture, in contrast to other continuously expressed genes. When gene expression was combined with electrophysiology, two subsets of genes were apparent; those irrelevant to spontaneous depolarizations (including vGLUT1, GIRK2, FOXP2 and DISC1) and those associated with spontaneous depolarizations (GAD1 and ERBB4). The results demonstrate that in the earliest stages of neuron development, it is useful to combine genetic analysis with physiological characterizations, on a cell-to-cell basis.

Disorders and borders: psychiatric genetics and nosology

Over the past century, the definition and classification of psychiatric disorders has evolved through a combination of historical trends, clinical observations, and empirical research. The current nosology, instantiated in the DSM-5 and ICD-10, rests on descriptive criteria agreed upon by a consensus of experts. While the development of explicit criteria has enhanced the reliability of diagnosis, the validity of the current diagnostic categories has been the subject of debate and controversy. Genetic studies have long been regarded as a key resource for validating the boundaries among diagnostic categories. Genetic epidemiologic studies have documented the familiality and heritability of clinically defined psychiatric disorders and molecular genetic studies have begun to identify specific susceptibility variants. At the same time, there is growing evidence from family, twin and genomic studies that genetic influences on psychiatric disorders transcend clinical boundaries. Here I review this evidence for cross-disorder genetic effects and discuss the implications of these findings for psychiatric nosology. Psychiatric genetic research can inform a bottom-up reappraisal of psychopathology that may help the field move beyond a purely descriptive classification and toward an etiology-based nosology.

Cognitive and behavioral trajectories in 22q11DS from childhood into adolescence: a prospective 6-year follow-up study

Patients with 22q11DS are at risk of behavioral problems and cognitive impairment. Recent studies suggest a possible intellectual decline in 22q11DS children. To date it is unknown if cognitive development is related to the behavioral problems in 22q11DS. We studied 53 children with 22q11DS who underwent cognitive and behavioral assessments at 9.5 years (T1) and 15.3 years (T2). In about one third, IQ data obtained at 7.5 years (T0) were also available. Results showed that internalizing behaviors intensified while externalizing behaviors decreased. Simultaneously, in about a third a significant decline in IQ was found, which, surprisingly, was unrelated to the behavioral changes. It can be concluded that children with 22q11DS follow a unique developmental trajectory. Cognitive deterioration is severe in some but does not appear to predict behavioral problems in early adolescence.

The relationship between autism spectrum disorders and attention-deficit/hyperactivity disorder: an overview

The autism spectrum has become a highly studied topic, perhaps the most researched of all developmental disorders. A host of related topics are being studied, with one of the most common being comorbidity of autism with other conditions such as epilepsy, sleep, and anxiety disorders. One of the most prevalent of these comorbid conditions is attention-deficit/hyperactivity disorder (AD/HD). A considerable amount of research has appeared on this topic with respect to symptom expression, prevalence of overlap, type of symptom overlap, and the effect of these two conditions co-occurrence on other symptoms and disorders. Given the substantial data base that has accrued, review and synthesis of these data are in order. This is the purpose of the present manuscript.

Genetic causes of developmental disorders

PURPOSE OF REVIEW

Developmental disorders, including intellectual disability, autism and attention deficit hyperactivity disorder (ADHD), are neuropsychiatric disorders that manifest in early childhood as deviations from the normal development. At present, in the majority of cases a cause cannot be found. However, in the past 5 years major advances have been made in the identification of specific genetic causes of these disorders. Here, we review these findings and discuss possible implications for our current understanding of the cause of developmental disorders.

RECENT FINDINGS

In addition to the disorders with known genetic cause that are associated with intellectual disability, autism and ADHD, an increasing number of novel recurrent structural variants are identified in association with these developmental disorders. These variants, as well as the genetic variants identified through sequencing approaches indicate the involvement of a large number of genes.

SUMMARY

Similar to what is the case for intellectual disability, recent genetic studies indicate a large degree of genetic heterogeneity for autism and ADHD. Many of the disease risk variants display incomplete penetrance, indicating that additional genetic, and possibly nongenetic, factors are relevant. Despite the high number of causative or contributing genes, functional studies of these genes indicate a large degree of convergence into a smaller number of neurobiological pathways. Elucidating these shared biological mechanisms is a crucial step towards the rational development of novel therapeutic interventions.

Attention deficit/hyperactivity disorder after neonatal surgery: review of the pathophysiology and risk factors

There are many factors that influence the long-term neurological outcomes in children following cardiac surgery. Because there is also complex interaction between these many factors, it is difficult to assess which are primary and modifiable and which can be used to make improvements in outcomes. As survival after complex neonatal heart surgery has increased, the number of children with long-term neurological deficits is becoming more evident and this affects quality of life for children and their families.

One area of long-term assessment is the incidence of attention deficit/hyperactivity disorder (ADHD). The incidence rate for ADHD following pediatric cardiac surgery is significantly higher than the normal rate for children of the same age. Because this is a measureable long-term outcome, it can be used to evaluate methods for cerebral protection during surgery as well as the timing of surgical procedures to maximize cerebral oxygen levels.

This paper will review the pathophysiological basis for ADHD in this population, based on the similarities between neonatal cardiac surgical patients and pre-term infants. Both populations have an increased risk for ADHD and the etiology and pathological changes in pre-term infants have been widely investigated over the past 25 years. The rate of ADHD in this population is a window into the effects of these pathological changes on long-term outcomes.

Reducing the incidence of ADHD in the future in this population should be a primary goal in developing and assessing new cerebral protective strategies during cardiac surgery.

Integrative mechanisms of oriented neuronal migration in the developing brain

The emergence of functional neuronal connectivity in the developing cerebral cortex depends on neuronal migration. This process enables appropriate positioning of neurons and the emergence of neuronal identity so that the correct patterns of functional synaptic connectivity between the right types and numbers of neurons can emerge. Delineating the complexities of neuronal migration is critical to our understanding of normal cerebral cortical formation and neurodevelopmental disorders resulting from neuronal migration defects. For the most part, the integrated cell biological basis of the complex behavior of oriented neuronal migration within the developing mammalian cerebral cortex remains an enigma. This review aims to analyze the integrative mechanisms that enable neurons to sense environmental guidance cues and translate them into oriented patterns of migration toward defined areas of the cerebral cortex. We discuss how signals emanating from different domains of neurons get integrated to control distinct aspects of migratory behavior and how different types of cortical neurons coordinate their migratory activities within the developing cerebral cortex to produce functionally critical laminar organization.

Mood disorders in youth: exercise, light therapy, and pharmacologic complementary and integrative approaches

The therapeutic value of physical exercise, bright light therapy and dawn simulation, and several pharmacologic treatments, including hypericum (St. John's wort), S-adenosylmethionine, and 5-hydroxytryptophan, are reviewed, with a focus on their use for treating major depressive disorder in children and adolescents and also for alleviating depressed mood in the general (nonclinical) population of youth. For each treatment discussed, all published randomized, double-blind, placebo-controlled trials are summarized, along with some additional selected studies. Nutritional psychopharmacology and several other approaches to treating depression will be presented in an upcoming volume in the Child and Adolescent Psychiatric Clinics of North America.

Autism spectrum disorders: the quest for genetic syndromes

Autism spectrum disorders (ASD) are a heterogeneous group of neurodevelopmental disabilities with various etiologies, but with a heritability estimate of more than 90%. Although the strong correlation between autism and genetic factors has been long established, the exact genetic background of ASD remains unclear. A number of genetic syndromes manifest ASD at higher than expected frequencies compared to the general population. These syndromes account for more than 10% of all ASD cases and include tuberous sclerosis, fragile X, Down, neurofibromatosis, Angelman, Prader-Willi, Williams, Duchenne, etc. Clinicians are increasingly required to recognize genetic disorders in individuals with ASD, in terms of providing proper care and prognosis to the patient, as well as genetic counseling to the family. Vice versa, it is equally essential to identify ASD in patients with genetic syndromes, in order to ensure correct management and appropriate educational placement. During investigation of genetic syndromes, a number of issues emerge: impact of intellectual disability in ASD diagnoses, identification of autistic subphenotypes and differences from idiopathic autism, validity of assessment tools designed for idiopathic autism, possible mechanisms for the association with ASD, etc. Findings from the study of genetic syndromes are incorporated into the ongoing research on autism etiology and pathogenesis; different syndromes converge upon common biological backgrounds (such as disrupted molecular pathways and brain circuitries), which probably account for their comorbidity with autism. This review paper critically examines the prevalence and characteristics of the main genetic syndromes, as well as the possible mechanisms for their association with ASD.

The BTBR mouse model of autism spectrum disorders has learning and attentional impairments and alterations in acetylcholine and kynurenic acid in prefrontal cortex

Autism is a complex spectrum of disorders characterized by core behavioral deficits in social interaction, communication, repetitive stereotyped behaviors and restricted interests. Autism frequently presents with additional cognitive symptoms, including attentional deficits and intellectual disability. Preclinical models are important tools for studying the behavioral domains and biological underpinnings of autism, and potential treatment targets. The inbred BTBR T+tf/J (BTBR) mouse strain has been used as an animal model of core behavioral deficits in autism. BTBR mice exhibit repetitive behaviors and deficits in sociability and communication, but other aspects of their cognitive phenotype, including attentional performance, are not well characterized. We examined the attentional abilities of BTBR mice in the 5-choice serial reaction time task (5-CSRTT) using an automated touchscreen testing apparatus. The 5-CSRTT is an analogue of the human continuous performance task of attention, and so both the task and apparatus have translational relevance to human touchscreen cognitive testing. We also measured basal extracellular levels of a panel of neurotransmitters within the medial prefrontal cortex, a brain region critically important for performing the 5-CSRTT. We found that BTBR mice have increased impulsivity, defined as an inability to withhold responding, and decreased motivation, as compared to C57Bl/6J mice. Both of these features characterize attentional deficit disorders in humans. BTBR mice also display decreased accuracy in detecting short stimuli, lower basal levels of extracellular acetylcholine and higher levels of kynurenic acid within the prefrontal cortex. Intact cholinergic transmission in prefrontal cortex is required for accurate performance of the 5-CSRTT, consequently this cholinergic deficit may underlie less accurate performance in BTBR mice. Based on our findings that BTBR mice have attentional impairments and alterations in a key neural substrate of attention, we propose that they may be valuable for studying mechanisms for treatment of cognitive dysfunction in individuals with attention deficits and autism.

Discussing the psychiatric manifestations of 22q11.2 deletion syndrome: an exploration of clinical practice among medical geneticists

PURPOSE

The aim of this study was to determine the frequency with which medical geneticists discuss the psychiatric manifestations of 22q11.2 deletion syndrome (22q11DS) with families in relation to the frequency with which they discuss the other manifestations of the syndromes and to explore relationships between discussion of these features and stigma toward psychiatric disorders.

METHODS

We surveyed medical geneticists in the United States and Canada regarding the frequency with which they discuss various features of 22q11DS with families in the context of four clinical scenarios in which only the age of the patient at diagnosis differed. Respondents also completed a 20-item validated psychometric measure of stigma toward psychiatric disorders.

RESULTS

308 of 546 medical geneticists completed the survey (56% response rate). Overall, psychiatric disorders were discussed significantly less often than other features of 22q11DS (P < 0.0001) but were discussed significantly more often when the patient was 13 years or older (P < 0.0001) than when the patient was younger. Geneticists who discussed psychiatric disorders the least had significantly higher levels of stigma toward psychiatric disorders (P = 0.007).

CONCLUSION

Psychiatric manifestations of 22q11DS are less often discussed with families during childhood. Education for physicians to help reduce stigma toward psychiatric disorders (which may impede discussion of psychiatric disorders) may warrant exploration in this population.

22q11 deletion syndrome: a review of the neuropsychiatric features and their neurobiological basis

The 22q11.2 deletion syndrome (22q11DS) is caused by an autosomal dominant microdeletion of chromosome 22 at the long arm (q) 11.2 band. The 22q11DS is among the most clinically variable syndromes, with more than 180 features related with the deletion, and is associated with an increased risk of psychiatric disorders, accounting for up to 1%-2% of schizophrenia cases. In recent years, several genes located on chromosome 22q11 have been linked to schizophrenia, including those encoding catechol-O-methyltransferase and proline dehydrogenase, and the interaction between these and other candidate genes in the deleted region is an important area of research. It has been suggested that haploinsufficiency of some genes within the 22q11.2 region may contribute to the characteristic psychiatric phenotype and cognitive functioning of schizophrenia. Moreover, an extensive literature on neuroimaging shows reductions of the volumes of both gray and white matter, and these findings suggest that this reduction may be predictive of increased risk of prodromal psychotic symptoms in 22q11DS patients. Experimental and standardized cognitive assessments alongside neuroimaging may be important to identify one or more endophenotypes of schizophrenia, as well as a predictive prodrome that can be preventively treated during childhood and adolescence. In this review, we summarize recent data about the 22q11DS, in particular those addressing the neuropsychiatric and cognitive phenotypes associated with the deletion, underlining the recent advances in the studies about the genetic architecture of the syndrome.

Expression of autism spectrum and schizophrenia in patients with a 22q11.2 deletion

BACKGROUND

Copy number variants (CNVs) associated with neuropsychiatric disorders are increasingly being identified. While the initial reports were relatively specific, i.e. implicating vulnerability for a particular neuropsychiatric disorder, subsequent studies suggested that most of these CNVs can increase the risk for more than one neuropsychiatric disorder. Possibly, the different neuropsychiatric phenotypes associated with a single genetic variant are really distinct phenomena, indicating pleiotropy. Alternatively, seemingly different disorders could represent the same phenotype observed at different developmental stages or the same underlying pathogenesis with different phenotypic expressions.

AIMS

To examine the relation between autism and schizophrenia in patients sharing the same CNV.

METHOD

We interviewed parents of 78 adult patients with the 22q11.2 deletion (22q11.2DS) to examine if autistic symptoms during childhood were associated with psychosis in adulthood. We used Chi-square, T-tests and logistic regression while entering cognitive level, gender and age as covariates.

RESULTS

The subgroup of 22q11.2DS patients with probable ASD during childhood did not show an increased risk for psychosis in adulthood. The average SRS scores were highly similar between those with and those without schizophrenia.

CONCLUSIONS

ASD and schizophrenia associated with 22q11.2DS should be regarded as two unrelated, distinct phenotypic manifestations, consistent with true neuropsychiatric pleiotropy. 22q11.2DS can serve as a model to examine the mechanisms associated with neuropsychiatric pleiotropy associated with other CNVs.